A backless slipper is a type of shoe that is open at the back and has no heel. The term can be used to describe four different types of footwear: a MULE (4 letters), an OTTOMAN (7 letters), a DIVAN (5 letters), and a STOOL (5 letters). A MULE is a type of slip-on shoe with no back or heel, while an OTTOMAN is a type of slipper with a low heel and no back. A DIVAN is a type of slipper with a low heel and a back, and a STOOL is a type of slipper with a low heel and a back that is higher than the front.